Blow molding apparatus

ABSTRACT

A process and apparatus for blow molding hollow plastic articles. The apparatus includes a pair of mold transport assemblies, one positioned on either side of the head of a plastic parison extruder. The mold transport assemblies reciprocate to carry the mold halves under the parison extruder to receive the parison and return to separate blow stations. The device utilizes a cam and cam follower mechanism for opening and closing the mold halves. The apparatus is movable for the purpose of mold setup. After mold setup is complete, the apparatus is mounted on a fixed platform beneath the extruder. The platform is adjustable in all directions to provide alignment of the apparatus with the extruder.

United States Patent [191 Kinslow, Jr. et al.

[ Jan. 14, 1975 BLOW MOLDING APPARATUS [73] Assignee: Ethyl DevelopmentCorporation,

Kansas City, Mo.

[22] Filed: Mar. 4, 1974 [21] Appl. No.: 447,826

Related U.S. Application Data [63] Continuation of Ser. No. 232,666,March 8, 1972,

abandoned.

[52] U.S. Cl 425/182, 425/186, 425/D1G. 203,

425/DIG. 206 [51] Int. Cl B29d 23/03 [58] Field of Search 425/D1G. 203,DIG. 204,

425/D1G. 205, DIG. 206, DIG. 211, DIG. 213,182,186, 326 B R25,29012/1962 Parfrey 425/326 B FOREIGN PATENTS OR APPLICATIONS 1,175,4188/1964 Germany 1,479,348 l/1972 Germany 1,905,267 8/1970 Germany1,921,379 11/1970 Germany 1,922,090 1 H1970 Germany 1,930,075 12/1970Germany OTHER PUBLICATIONS German Utility Model 1937084 dated February9, 1966 by G. Mehnert.

Primary Examiner-Richard B. Lazarus Attorney, Agent, or Firm-Donald L.Johnson; John F. Sieberth; E. Donald Mays [57] ABSTRACT A process andapparatus for blow molding hollow plastic articles. The apparatusincludes a pair of mold transport assemblies, one positioned on eitherside of the head of a plastic parison extruder. The mold transportassemblies reciprocate to carry the mold halves under the parisonextruder to receive the parison and return to separate blow stations.The device utilizes a cam and cam follower mechanism for opening andclosing the mold halves. The apparatus is movable for the purpose ofmold setup. After mold setup is complete, the apparatus is mounted on afixed platform beneath the extruder. The platform is adjustable in alldirections to provide alignment of the apparatus with the extruder.

14 Claims, 28 Drawing Figures 1 72 117 fwd M n, 71

PATENIEI] JAN 1 M975 sum 01 0F 13 PATENTEDJANWBYE' 3.880.375 SHEET 030F13 J PATENTED A-14l975 3,860.375

sum cu or 13 FIG. 7.

PATENTED JAN 1 4191s sum um 13 FIG. I3.

, [SS Rm PATENTED JAN 1 4197s SHEET 03 0F 13 FIG. 25.

PATENTED JAN 1 41975 SHEET 1OUF 13 FIG. I7.

ilg il PATENTEU 3.860.375

SHEET 11 0F 13 FIG. 20.

FIG. 22.

PATENTEU JAN 1 41975 SHEET lEUF 13 FIG. 23.

BLOW MOLDING APPARATUS This is a continuation of application Ser. No.232,666, filed Mar. 8, 1972, now forfeited.

BACKGROUND OF INVENTION 1. Field of the Invention This invention relatesto a method and apparatus for blow molding hollow plastic containers.

2. Description of the Prior Art Early models of thermoplastic blowmolding machines for producing hollow plastic containers utilized afixed plastic extruder which extruded a parison downwardly between twoopen mold halves adapted to be closed around the parison. These moldhalves were carried by movable platens, usually actuated with hydraulicor mechanical toggle devices with one-half of the mold being positionedon each side of the extruder. While many of these types of blow moldingmachines are still in use today, they suffer many disadvantages whichhave been overcome by some of the more modern machines on the market.Generally, the older machines require either that the plastic feed screwbe stopped or that a valve be closed to interrupt the flow of theplastic material to enable the parison to be cut and blown by the moldwhich was fixedly positioned directly beneath the extruder outlet. Whilethis is not particularly detrimental when extruding non-heat-sensitivepolymers, such as medium, low and high density polyethylene, it is adecided disadvantage when extruding heat-sensitive polymers, such aspolyvinyl chloride. It is highly desirable to continuously move theheatplastified polyvinyl chloride through the extruder and into the blowmolding apparatus in a continuous manner to avoid heat degradation.

In recent years, blow molding machines have become available whichpermit the continuous extrusion of the plastic parison and subsequentformation of hollow plastic containers therefrom by machines whichutilize two different principles. In some of the older machines, theparison was continuously extruded, and trapped segments thereof werereceived between traveling mold halves which were brought together bycams or tracks or by hydraulic means as they gripped the parison. Thesemold halves were carried on separate wheels which were adapted to rotateeither in the horizontal or in the vertical plane. Machines designed onthis principle found some commercial utility; however, the maintenancecosts and the inability to maintain the close precision tit required forthe operating components have lead to a rapid decline in the use of thistype of blow molding apparatus. Additionally, when larger containersbecame popular, the operating difficulties of the rotary machines weremagnified.

The more recent high speed machines adapted to continuously extrude aplastic parison and to continuously carry out blow molding, cooling andejection steps have found wide commercial use in all parts of the world.These machines utilize the basic principle taught in U.S. Pat. No. Re.25,290 wherein the mold halves are reciprocated underneath the fixedextruder head to receive the parison and then reciprocated back againover the same path to a blow station where the parison trapped betweenthe mold halves is blown to the contour of the mold, cooled and ejectedtherefrom. The commercial versions of machines operating according tothe principle of the above-noted Parfrey patent utilize blow moldscarried on platens which are supported on mold transport assembliesadapted to move the mold halves underneath the extruder head.Dualstation, reciprocating, blow molding machines commercially availableutilize extremely complex construction. The mold transport mechanisms,the extruder frame and accessory parts are usually built into one large,integrated unit. The mold transport assemblies and the mold closingpower means are usually actuated by hydraulics. One of the primedisadvantages of commercially available, dual-station, reciprocating,blow molding machines is the fact that the user cannot repair onecomponent or one element of the machine without shutting down themachine operation completely. If a malfunction occurs in one of the blowmolding stations, i.e., the mold transport assembly or the blow pinassembly, it is generally necessary to close the complete machine downin order to service one-half of the blow molding parts of the machine.Additionally, when the mold setup is being made on the machine, thecomplete machine is down and out of service for the full length of timeit takes to remove the old mold halves, replace with the new mold halvesand to make a test run using the new mold halves.

One of the more commonly used, reciprocating, dual-station, blow moldingmachines is that described in the magazine Plastics, April, 1965(published in Great Britain). This machine incorporates two moldingstations which are operated alternately so that dual production isachieved from a single extruder and parison head. Each set of moldhalves moves on a diagonal path and is powered by hydraulic cylinders.Another twostation, alternately operated, blow molding apparatus similarto the above described machine moves each set of mold halves in anarcuate path from the blow mold station to the parison extrusion stationand back again.

From the foregoing, it is seen that the blow molding industry is in needof a dual-station, blow molding machine wherein each of the stationsutilizes an integral, self-contained, blow molding subassembly. Thesubassemblies are mounted on a base which is capable of being removedfrom the outer portions of the blow molding machine for mold setup andmaintenance. This provides the industry with a blow molding machinewhich has the capability of being set up in a location different fromthe location of the extruder and platform components.

SUMMARY OF THE INVENTION It is an object of the present invention toprovide a method and apparatus for blow molding containers with adual-station, blow molding machine.

It is another object of the present invention to provide a method andapparatus for blow molding containers wherein the blow moldingsubassemblies and their base can be separated from the remainder of themachine.

It is still another object of the present invention to provide a methodand apparatus for blow molding containers which utilize pneumatic powermeans.

It is also an object of the present invention to provide an apparatusfor blow molding plastic containers which provides positive, lowmaintenance power means for closing the blow mold halves.

It is still another object of the present invention to provide a methodand apparatus for blow molding plastic containers which utilize a novelmechanism for opening and closing the blow molds.

The foregoing objects and other advantages that are brought outhereinafter are realized in the apparatus aspects of the presentinvention in an apparatus for blow molding plastic containers whichincludes means for supplying a tubular parison of moldable plasticmaterial at a parison supply station. A first means is provided fortransversely moving a first pair of blow mold halves to the parisonsupply station to receive the parison and to return the parison to ablow station. A second means is provided for transversely moving asecond pair of blow mold halves to the parison supply station to receivea parison and to return the parison to a second blow station. Means arecarried by the first and second means for transversely moving the firstand second pair of blow mold halves for opening and closing the blowmold halves. A first, fixedly mounted blow pin assembly is positioned toengage the first pair of blow mold halves at a first blow station toexpand the enclosed parison. A second, fixedly mounted blow pin assemblyis positioned to engage a second pair of blow mold halves at a secondblow station to expand the enclosed parison.

The process aspects of the present invention are realized in a processfor blow molding plastic containers which includes supplying a first,thermoplastic parison from a fixed extrusion station. A first, splitblow mold, which is located at one side of the extrusion station ismoved to the extrusion station in a path which is substantiallyperpendicular to the axis of the first parison. The path of the blowmold is changed to an upwardly inclined path over the last few inches oftravel as the blow mold reaches the extrusion station. The parison isenclosed in the first blow mold, and it is returned over the same pathon which it approached the extrusion station. The parison is then blownto form the container at the blow station. A second blow station and asecond blow mold may be located on opposite sides of the extrusionstation to carry out the above described process alternating with thefirst blowmold.

One of the prime advantages of the apparatus of the present invention isthat the major part of the blow mold apparatus is completelytransportable and readily movable from one location to another, forexample, by use of a forklift truck. This mobility permits the blow moldapparatus of the present invention to be utilized with a permanentlylocated extruder which is completely separate and does not have to beconnected to the blow mold apparatus. Another of the significantadvantages of the blow mold apparatus of the present invention is theutilization of pneumatic power for actuating the mold transportsubassemblies, the mold closing mechanism for the mold halves, and theblow pin assembly. The advantages of pneumatic power over hydraulic oroil power are well known, e.g., comparatively low operating pressures,fluid leak-resistant lines, cleaner operation due to absence of oilleaks, less contamination of product from oil spills and drips, 'andlower operating costs because of utilization of air pressure from acentral source rather than requiring independent hydraulic drives foreach extruder and blow mold setup. The blow mold apparatus of thepresent invention also has a distinct advantage in the utilization of acam and cam follower mechanism for driving the platens which carry theblow mold halves. Heretofore, direct drive, hydraulically actuatedcylinders have been used to close the platens and, thus, the mold halvestogether around the parison. This requires heavy castings and highenergy power sources to operate through X-or toggle linkages to achievethe required closing pressures for an efficient blow molding operation.The novel cam and follower mechanism used in the blow molding apparatusof the present invention is characterized by its simplicity, its freedomfrom maintenance and its high operational dependability. A furthersignificant advantage of the apparatus of the present invention is foundin the utilization of rotary, linear, pneumatically poweredsubassemblies for driving the cam and cam follower mechanism to open andclose the mold halves and also to furnish power to the mold transportsubassemblies for moving the molds into position under the extruder andretracting the molds to the blow station. These units are simple inconstruction, highly dependable and readily maintained.

Other advantages and novel features of the invention will be describedhereinafter in connection with the description of the embodiments foundin the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view of adual-station blow molding apparatus constructed in accordance with thepresent invention;

FIG. 2 is a front, elevational view of the blow mold apparatus of FIG.1;

FIG. 3 is a right-hand-side, elevational view of the blow mold apparatusof FIG. 2;

FIG. 4 is an enlarged, top plan view of the mold transport subassemblyutilized in the present invention;

FIG. 5 is a front, elevational view of FIG. 4 showing the mold carryingplaten;

FIG. 6 is a right-hand-side, elevational view of the mold carryingsubassembly of FIG. 4.

FIG. 7 is a longitudinal, sectional, elevational view of the pneumaticpower subassembly used in the blow mold apparatus of the presentinvention;

FIG. 8 is an enlarged, partially sectional, partially elevational viewof the blow pin assembly used in the blow mold apparatus of the presentinvention;

FIG. 9 is a right-hand-side, elevational view of the blow pin assemblyof FIG. 8;

FIG. 10 is a partially broken, sectional view of the apparatus of FIG. 9taken along line 10-10;

FIG. 11 is an exploded, elevational, perspective view of anotherembodiment of the stripper mechanism for the blow pin assembly of thepresent invention;

FIG. 12 is a front, elevational view of another embodiment of thepresent invention showing multiple blowing heads on the blow pinapparatus of the present invention;

FIG. 13 is an exploded, elevational, perspective view of the stripperassembly for the blow pin apparatus seen in FIG. 12;

FIG. 14 is a top plan view of the base assembly for the blow moldingapparatus of the present invention with the left-hand transport andactuating assembly mounted thereon;

FIG. 15 is a front, elevational view of the base assembly for the blowmold apparatus of the present invention with the right-hand transportand actuating assembly.mounted thereon;

FIG. 16 is an enlarged, broken, elevational view of the base of thepresent invention showing the position l .of the linkage connecting thepower means and the transport assembly;

FIG. 17 is a top plan view, partially broken, showing one embodiment ofthe pedestal assembly for mounting q the blow molding apparatus of thepresent invention; FIG. 18 is a front, elevational view of the pedestalassembly of FIG. 17;

FIG. 19 is a right-hand-side, elevational view of the pedestal assemblyof FIG. 18;

FIG."20 is a top plan view, partially broken, showing ",ried by thesupport frame and are adapted to alteranother embodiment of the pedestalassembly for. mounting the blow molding apparatus of the presentinvention;

FIG. 21- is a front, elevational view of the pedestal assembly of FIG.20;

FIG. 22 is a right-hand-side, elevational view of the pedestal assemblyof FIG. 20; FIG. 23 is an enlarged, front, elevational viewof theforward platen adjustment assembly; 7

FIG. 24 is a cross-sectional view of FIG. 23 taken on line 24-24;

FIG. 25 is a cross-sectional view of the mold transport subassembly ofFIGS. 4 and 6 taken along line FIG. 26 is a top plan view of thetravel'cushion assembly;

FIG. 27 is a left-hand-side, elevational view of the travel cushionassembly of FIG. 26; and

FIG. 28 is a rear, elevational view of the travel cushion assembly ofFIG. 26. I

DESCRIPTION OF THE PREFERRED Y EMBODIMENTS Referring'now to FI GS. l, 2and 3, the blow molding apparatus of the present invention is designatedby the numeral 35. The apparatus includes a support frame designatedgenerally by the numeral 36. The support frame includes a generallyrectangular, heavy, metal base member 37. A pair of side frame members38-38 are welded tothe base member 37 at one edge and extend upwardlytherefrom. The side frame members are provided with a number of openings41 therein to permit access to the interior of the support frame. Endframe members 39-39 are weldably attached to the ends of side members 38to provide a rigid support frame structure. A left-hand, upwardlyextending bracket member having a generally L shape and desig nated bythe numeral 45 is attached by welding or other suitable means to thefront side plate 38 and the base member 37 of the frame as seen in FIGS.2 and 15. A

nately move between the blowstation, in which position they are depictedin FIGS.,11, 2 and 3, and the parison-receiving station immediatelybeneath the extruder 47. As seen in FIGS. 5 and 6, each of the.transport and actuating assemblies includes two front V wheels 48-48which are adapted to'ride on the rail 43 of the I support frame. Rearflat wheels 48a-48a ride on lower flat rail 40. As seen more clearly inFIG. 6, the lefthand-V wheels 48-48 have a V-shaped bearing surface toinsure that the transport mechanism does not move transversely when itis-being transported back and forth across the carriage 'rails. The blowmold transport and actuating assemblies include a frame structure,designated generally 49. The frame structure includes a base plate 50,as seen more clearly in FIGS. 4 and 6, having attached to-each sidethereof side frame members 51-51. The frame structure 49 may be madefrom cast metal or it may be made from heavy r'iietal stock by weldingor other suitable means. An upper, centrally positioned bushing member52 extends between the sidewall frame members 51-51 and is weldablyattached, or attached by other suitable means, thereto. Lower bushingmember 53 is likewise attached between the side frame members 51-51 atthe forward end of the blow mold transport and actuating assembly. Anupper tie bar 54 is slidably received in upper bushing 52 and projectsfrom each end thereof. A lower tie bar 55 is slidably received in lowerbushing 53 and ex- 1 tends from each end thereof. The forward ends oftie like right-hand, L-shaped bracket 46 is attached to the right-handside of the support frame in the same manner.

As seen in FIGS. 6, 14, 15 and 16, the back side member 38 is providedwith a lower support flat rail 40 and upper flat guide rail 40c attachedthereto. The front side member 38 is provided with lower V rail 43 andan upper V guide rail 42 attached thereto. As seen in FIG. 15, the lowerV rail 43-is divided into forward segments 43a-43a and rearward segments43b-43b. Each of the rail segments 43a-43b'0f the left side member 38terminates in an upwardly directed, arcuate end section designated 44.As seen in FIG. 16, lower flat rail 40 is likewise divided into forwardflat rail sections 40a-40a and rearward flat rail sections 40b-40b. Eachrail section 40a-40b on right side bars 54 and 55 are threaded and arereceived in openings provided in forward platen 56 which is attached tothe tie bars by means of nuts 57. As seen in FIG. 5, a plurality of boltholes 58 are provided in the forward 'platen 56 which receive bolts forholding the outer mold half 56a against the inner face of the platen. Arearward platen 59 is slidably mounted on tie bars 54 and 55 by means ofintegral, elongated bushings 60-60 as can be seen more clearly in FIG.6. The rearward platen 59 has the same general shape as the forwardplaten 56 and is also provided with holes therein (not shown) forattaching inner mold half 59a thereto by means of bolts.

The rear portion of the tie bars 54 and 55 is provided with threads 61.A forward platen adjustment assembly, designated generally by thenumeral 62, is mounted on the rear ends of tie bars 54 and 55 and isadapted to be moved over the threaded portions 61-61 thereof.

As will be seen more clearly in FIGS. 23 and 24, the forward platenadjustment assembly includes a generally eliptical cast housing sectionl42..The housing is closed by cover plate 143 which is attached to thehousing by means of bolts 144 received in threaded openings provided inthe walls of the housing. Additional strength is provided in theadjustment assembly by means of spaced apart, integrally formed bosses145-145 which project forwardly in the housing and provide anchor meansfor the cover plate through additional bolts 144. The central portion ofthe back .wall 146 of the housing is provided with an annular recess 147which receives the end of cylindrical shaft 148 which is rotatablymounted in the recess by means of bushing 149. The forward end of shaft148 is received in a hub 150 which is attached to cover plate 143 bywelding or other suitable means. Bushing 151 is provided between the hub150 and the shaft 148 for rotation of the shaft. Sprocket 152 is fixedlymounted on shaft 148 by means of pins 153. Sprocket 152 is provided witha forward set of teeth 152a and a spaced apart, rearwardset of teeth152b. Drive chain 154 connects the forward set of teeth 152a to asprocket 155 which is threadably mounted on the threaded end 61 of lowertie bar 55. Inner and outer ends of the sprocket 155 are rotatablymounted in the back wall 146 and the cover plate 143, respectively, forrotation therein utilizing bushings.

Rearward sprocket teeth l52b are connected by drive chain 156 tosprocket 157 which is threadably received on the threaded end 61 ofupper tie rod 54. The inner end of the sprocket is received in the rearwall 146 of the casting and provides for rotation through a bushing,and, likewisepthe forward end is received in a bushing set in an openingin the cover plate 143 whereby the sprocket 157 may be rotated on theshaft 54.

A tension adjust assembly, designated generally by the numeral 158, ismounted on the outer end of the fixed bushing 151. Takeup assemblyincludes a generally elliptical shaped bracket 159 which is mounted onthe outer end of bushing 151 and is fixedly attached thereto by means oflocking screw 160. The right-hand end of bracket 159 is provided with aninwardly extending, cylindrical shaft 161 which passes through anarcuate slot 162 in the cover plate 143. The inner end of shaft 161 isprovided with an idler sprocket 163 rotatably mounted thereon whichengages drive chain 156 to provide the correct amount of tension forthis chain. Left-hand end of bracket 159 is provided with an inwardlyextending shaft 164 which passes through arcuate opening 165 provided inthe cover plate. The inner end of shaft 164 is provided with idlersprocket 166 rotatably mounted thereon, which sprocket engages forwarddrive chain 154 to provide the correct tension for this chain. Tensionadjustment on drive chains 154 and 156 may be made by loosening lockingscrew 160 and rotating bracket 159 in either the clockwise orcounterclockwise direction to provide the proper tension on thesechainsand then tightening screw 160 to lock the brakcet to the collar orhub 150.

If desired, the threaded ends of the upper tie bar 54 and the lower tiebar 55 may be provided with locking collars 167 which are threadablyreceived on the tie bars and may be clamped thereto by means .of setscrews 168 to prevent movement of the platen adjust assembly 62 afterthe assembly has been properly positioned.

In operation, the forward platen adjust assembly 62 is actuated byattaching a suitable wrench to the end of center shaft 148 and rotatingthe shaft either clockwise or counterclockwise to drive the sprockets155 and 157 threadably connected to the tie bars 54 and 55 in thedirection desired. By rotation of the sprockets S and 157, the upper andlower tie bars may be pulled in or pushed out to, in turn, move theforward platen 56 either closer to or farther away from the rearwardplaten 59. Thus, by adjusting the forward platen 56, the space betweenthe platens can be changed to accommodate any size split blow mold.

The platen adjustment assembly 62 has an anchor block 63 attached to therear side thereof. An upper push-pull rod 64a and a lower push-pull rod64b have their outer ends received in the anchor block and extendoutwardly therefrom. The upper and lower pushpull rods 64a and 64b passthrough a bushing block 65 which is attached to the outside ofright-hand sidewall 51. The inner ends of push-pull rods 64a and 64b arejoined together by means ofa pin 66, as seen in FIG. 4, on which isrotatably received a roller bearing assembly 67.

Referring now to FIG. 6 in particular, the rearward platen,59 has arearwardly extending, integrally formed anchor block 68 thereon. Theforward ends of a second pair of push-pull rods are received in theanchor block 68. Upper push-pull rod 69a and lower push-pull rod 69b areof similar construction and length as hereinbefore described push-pullrods 64a and 64b. Push-pull rods 69a and 69b extend through left-handsidewall 51 and are slidably received in a left-hand bushing block 70mounted on the sidewall. The inner ends of pushpull rods 69a and 69b arejoined by pin 66, as seen in FIG. 4, which carries a roller bearing 67thereon in the same manner as the opposite push-pull rods 64a and 64bdescribed above. I

Referring now to FIGS. 1, 3 and 4-6, the blow mold transport assemblyincludes a fluid power assembly, designated generally by the numeral 71,which is mounted on the base plate 50 of the frame. The power assemblyoperates to move the platens 56 and 59 together and away from each otherto close and open the mold halves carried oneach of the platens. Thepower assembly includes a double-acting, pneumatic power cylindersubassembly, designated generally by the numeral 72. As seen moreparticularly in FIG. 7, the double-acting power cylinder 72 includes agenerally rectangular left end housing 73a and a right-hand rectangularend housing 73b. End housings 73a and 73b have received therebetween inan airtight seating relationship a central section which includes amaster power cylinder section 74. Mounted below the master powercylinder 74 is a pilot cylinder 75. Piston 76 is slidably receivedinside master cylinder 74. A small pilot piston 77 is likewise receivedin pilot cylinder 75. A righthand sprocket gear 78 is contained in rightend housing 73b and is rotatably mounted thereon by means of shaft 79 towhich the sprocket gear is keyed. A left-hand sprocket gear 80 ismounted in left end housing 73a and is carried on shaft 81 which rotatesin bearing blocks (not shown) attached to the walls of the housing 73a.A I drive chain 82 is carried by the right-hand sprocket gear 78 and theleft-hand sprocket gear 80 and is coupled to the master piston 76 and tothe pilot piston 77. The ends of master cylinder 74 and pilot cylinderare open and communicate with the end housing 73a and 73b to permit thechain 82 to move freely therebetween. Compressed fluid for operating thepneumatic, double-acting power assembly 72 is supplied through hoses orconduits 73c-73c provided at each end housing 73a and 73b. Byalternately admitting compressed fluid such as air or compressednitrogen or other gaseous fluids to the respective end housing chambers73a and 73b, the master piston 76 is caused to reciprocate back andforth within the cylinder 72 producing rotation of drive shaft 81. Thedegree of rotation of drive shaft 81 is controlled by the length of thecylinder 74 and, thus, the travel permitted for the power piston 76. Inthe pneumatic power cylinder 72 of the present machine, the stroke islimited to that necessary to drive the shaft through an arc of about 115degrees. A suitable commercially available pneumatic power cylinder ismanufactured by Graham Engineering Company.

Referring now to FIGS. 4, 6 and 25, the power cylinder assembly 72 ismounted on the bottom plate 50 of the frame 49 by means of a keywayplate 83 at each end of the frame underneath the housing ends 73a and73b of the power cylinder assembly. The keyway block 83 is attached tothe frame by mean of bolts 83a. The keyway block 83 slidably receives akeyway slide 84 which is, in turn, attached to the bottom of the endhousing 73a and 73b of the power cylinder assembly. The keyway slides84-84 each have an axially directed, threaded bore therein. A threadedrod 86 has one end received in the threaded bore in each of the keywayslides 84-84. The right-hand threaded rod 86 has its outer end rotatablyjourneled in a bearing provided in left-hand sidewall 51. The outer endof rod 86 terminates on the outside of left-hand wall 51 in the form ofa rectangular drive nut 87. The left-hand threaded rod 86 is alsojourneled in a bearing in the left-hand sidewall 51, but does not have adrive nut on the end thereof. A drive sprocket 88 is keyed on each ofthe threaded rods 86-86. The sprockets 88-88 are connected by means of adrive chain 89 whereby they may be rotated together to position thepower cylinder assembly.

By rotating the right-hand drive rod 86 by means of drive nut 87, thedrive rod 86 is screwed in or out of the keyway slide 84 moving thisslide transversely in the keyway block 83 and, thus, moving the rear endof the power cylinder 72 between the sidewalls 51-51 of the frame. Asright-hand rod 86 rotates, it also drives lefthand rod 86 through thetwo sprockets 88-88 and the drive chain 89 to position the forward endof the power assembly 73a in exactly the same position as the rear endof the assembly. Thus, the mechanism provides a means for transverselyshifting the pneumatic, doubleacting power cylinder between thesidewalls of the frame which, in turn, shifts the center line positionof the mold platens 56-59 and the mold halves 56a-59a toward or awayfrom the blow mold and transport actuating assembly 47a. This permitsexact alignment of the blow mold center line with the extruder 47.

Attached to drive shaft 81 of the pneumatic, doubleacting power cylinder72 is a mold closing cam 90. Cam 90 is attached to the drive shaft 81 bymeans of a flange 91. The lower position of shaft 81 extends through abushing 92 mounted on the top of the forward end 73b of the pneumatic,double-acting power cylinder 72. Cam 90 is provided with two opposed,generally J- shaped cam openings 93a and 93b as may be seen more clearlyin FIG. 4. Left cam opening 93a receives the roller bearing 67 carriedby upper and lower push-pull rods 64a and 64b. The right-hand camopening 93b receives a roller bearing 67 which is carried by the upperand lower push-pull rods 69a and 69b.

Referring now to FIGS. 6, 14, and 16, the righthand mold transport andactuating assembly 47a is moved over the support frame 36 by means of arighthand transport or power assembly, designated generally by thenumeral 94a. The left-hand blow mold transport and actuating assembly47b is likewise transported on the frame 36 by means of a left-handtransport power assembly, designated generally by the numeral 94b. Theseunits are identical in construction and in operation.

Each of the transport or power assemblies 940 and 94b include apneumatic, double-acting power cylinder 72 of exactly the sameconstruction and operation as described hereinbefore in connection withthe blow mold transport and actuating assembly 470. The drive shaft oneach of the power units 72-72 is coupled to the power shaft 95 of thepower assembly by means of a detachable coupling 96 as seen more clearlyin FIG. 14. Drive shaft 95 is carried by a pair of spaced apart bearingblocks 97-97 which are attached to bottom plate 37 of the frame 36. Theshaft rotates in these bearing blocks over an arc of approximately 190degrees. The shaft has keyed to it between device 97-97 a drive arm 98which is reciprocated by the shaft 95. Pivotably connected to the end ofdrive arm 98 is pivot arm 99. Pivot arm 99 is pivotably coupled to thebracket 100 which is attached to and extends below the bottom of thebase plate 50 of the frame 49 and, thus, propels the blow mold transportand actuating assembly 47a back and forth over rails 40 and 43. Pins101-101 at each end of the pivot arm are used to attach the pivot arm 99to drive arm 98 and to bracket 100.

As seen more clearly in FIGS. 1, 2, 3, 8, 9 and 15, each of the leftandright-hand L-shaped brackets 45 and 46 have extending therefrom atransverse arm 45a and 46a, respectively. The arms are provided with aplurality of vertically arranged holes 103 therethrough as may be seenmore conveniently in FIG. 15. Brackets 104-104 are mounted on transversearms 45a and 46a by means of bolts 105 which extend through the holes103 of the bracket arms. As seen in FIG. 12, the bolts 105 are receivedin horizontal slots 106 provided in the back wall of the bracket 104. Bythis arrangement, the position of brackets 104-104 can be adjusted inthe horizontal plane on the bracket arms 45a and 46a. Attached to thetop of brackets 104-104 are support plates 107-107 which are attached tothe brackets by means of bolts 102. Mounted on support plates 107-107and extending above and below the plates are blow assemblies, designatedgenerally by the numeral 108-108. Each blow assembly includes adouble-acting, pneumatic power cylinder 109 which extends verticallyabove the support plate 107 and is mounted thereon by means of flange110. As seen in FIG. 8, a piston rod having a threaded end 111 extendsfrom the power cylinder 109 through the flange 110 and a hole providedin the support plate 107. Threaded end of piston rod 111 is threadablyreceived in a flange 1 l2 and is locked thereto by means of nut 113received on the threaded end of the piston rod. A rectangular supportframe 114 is attached to the flange 112 by means of bolts 115. As seenin FIGS. 8 and 10, the lower wall of the support frame 114 is providedwith three large openings 116 spaced equally across the length of theframe. A blow pin assembly, designated generally 117, is attached to theframe 114 by means of knurled nut 118.

Referring now in particular to FIGS. 8, 9 and 11, a stripper plate 119is mounted adjacent the end of blow pin assembly 117 by means of a pairof hanger rods 120-120 which have their upper ends received in supportplate 107 and are held thereon by means of nuts 121. The upper surfaceof the stripper plate 119 pro vides a large central opening 122 therein.The surface of the stripper plate 119 surrounding the opening 122 isrecessed at 123. Stripper ring or washer 124 is received in the recess123 provided in the face of the stripper plate 119. Stripper ring 124 isheld in the recess by means of a hold plate 125 abutting the top of thestripper ring 124 and held thereon by means of bolts received inopenings 126 tapped in the surface of the stripper plate 119. Theopening in the stripper ring is sized slightly larger than the diameterof the cylindrical barrel of the blow pin assembly 117 and is adapted tostrip off the neck moil or waste portion of the plastic article blown inthe machine as the blow pin is retracted through the opening in thestripper ring 124.

As seen in FIGS. 9 and 10, the support frame 114 is provided with a pairof cars 127-127 which have openings 128-128 of sufficient size to freelyreceive and permit passage of the frame 114 up and down the two tie rods120-120. This maintains the orientation of the frame 114 and, thus,insures alignment of the blow pin assemblies 117 which are mountedthereon.

Referring now to FIGS. 12 and 13, a second embodiment of the lowerportion of the blow assembly 108 is depictd. The assembly utilizes thesame support frame 114 as the embodiment shown in FIGS. 8 and 9;however, three blow pin assemblies 117-117-117 are mounted on the frame114 by means of knurled nuts 118-118-118. An alternate stripper plate129 is provided which has three large openings 130-130-130 providedtherein. The top of plate 129 in the area surrounding the openings 130is provided with annular recesses 131-131-131. Into each recess isfitted a stripper ring or washer 132, each of which has an opening 133slightly larger than the diameter of the cylinder portion of the blowpin assembly 117. A holder plate 134 is provided with openings 125 whichare aligned with the openings 133 and 130 provided in the stripperwashers and the stripper plate. The holder plate is retained on the topof the stripper washers 132 by means of bolts 136 received in threadedtapped openings 137 provided in the stripper plate 129. When this typeof blow pin assembly arrangement is utilized, it is possible to utilizea blow mold having three mold cavities on the platens of the blowmolding machine and to blow three separate containers on each side ofthe machine in one step.

Referring now to FIGS. 8 and 9, an electrical microswitch assembly 138is attached to support plate 107 by bracket 139. The back of the bracketprovides vertical slots 140 therein in which are received bolts 141.This mounting arrangement permits the vertical adjustment of themicroswitch138 to actuate at the proper height of retraction of the blowpin assembly 117.

Referring now to FIGS. 2, 3 and 17-19, the blow molding apparatus of thepresent invention is mounted on a pedestal assembly, designatedgenerally by the numeral 169. The pedestal or platform assembly providesmeans for adjusting the position of the blow molding machine relative tothe extruder head 47 whereby the blow molding apparatus may be adjustedin all three planes. The pedestal or platform assembly includes a lowertable 170 which is in the form of a rectangular. heavy steel plate whichrests upon the floor 171. Mounted at the four corners of the lower tableassembly are jacks 172 having shafts 173 which, in their lower position,are received in recesses provided in the floor. The jacks may be of anyheavy-duty, commercially available type, for example, those driven by aworm gear assembly. The drive assembly for the lower assembly jacksincludes a shaft 174 on the right-handcorner jack, which shaft isprovided with a hexagonal head for receiving a drive wrench. The shaft174 is connected at its outer end, as can be seen in FIG. 19, to driveshaft 175 which includes two universal joints 176-176. Shaft 175 iscoupled to shaft 177 of the right-hand rear jack which, in turn, hasmounted on the outer end of shaft 177 a drive sprocket 178. Sprocket 178carries drive chain 179. Drive chain 179 passes over idler-adjustsprocket 180. The left-hand set of jacks are coupled to the right-handset of jacks through drive chain 179 and are driven through a shaftcoupling assembly the same as described hereinbefore for the right-handjacks.

A second or middle table subassembly, designated generally by thenumeral 181, is fixedly attached to the upper end of the four shafts 173extending from the jacks of the lower table subassembly. An outermounting block 182 is fixedly attached, by welding or other means, tothe upper surface of middle table 183 at each corner. An inner mountingblock 184 is spaced opposite each outer block 182 and is fixedlyattached by welding or other means to the top surface of middle table183. A cylindrical support shaft 85 extends through openings provided ineach set of mounting blocks 182-184. A cylindrical guide sleeve 186 ismounted between the inner mounting blocks 184-184 at each end of themiddle table 183 and extends through an opening provided therein.Cylindrical guide shaft 187 is slidably received in the guide sleeve 186and has its lower end attached to the upper surface of lower tableassembly 170.

A third or top table subassembly, designated generally by the numeral188, is mounted above the middle table and is movably coupled thereto.This assembly includes a top table 189 having generally the same shapeas that of the middle and lower tables. A slide block 190 is positionedbetween each set of mounting blocks 182-184 provided on the middle table183 of the pedestal assembly. Each slide block 190 is provided with abore therethrough which receives the cylindrical support shaft and isslidably positioned thereon. Support blocks 191 and 192 are mountedopposite slide block and are attached to the underside of top table 189by means of welding or other suitable means. Cylindrical support shaft193 is received in openings provided in support blocks 191 and 192 andhas its outer end received in slide block 190 and pinned thereto bymeans of a key (not shown) or other suitable means. A support wheel 194is mounted on each shaft 193 between each set of support blocks 191-192.As seen in FIG. 18, the wheels 194 support the top table assembly 188 byriding on the supper surface of the middle table 183.

The position of the top table 189 is adjustable along the Z-axis of thepedestal assembly by means of a Z- axis adjust mechanism, designatedgenerally by the numeral 195. The Z adjust mechanism includes an outershaft 196 having its outer end extending through bracket 197 which isattached at its lower end to middle table 183. The shaft is providedwith a universal joint 198 and has its inner end connected to a T gear-

1. In an apparatus for extrusion blow molding plastic containers: a.means supplying downwardly extruded, tubular parisons of moldableplastic material at a parison supply station; b. a first means fortransversely moving with respect to the axis of said parisons a firstpair of blow mold halves to said parison supply station to receive afirst parison and to return said parison to a first blow station; c. asecond means for transversely moving with respect to the axis of saidparisons a second pair of blow mold halves to said parison supplystation to receive a second parison and to return said parison to asecond blow station; d. means carried by said first and said secondmeans for transversely with respect to the axis of said parisons movingsaid first and second pair of blow mold halves for opening and closingsaid blow mold halves; e. a first fixedly mounted blow assemblypositioned to engage said first pair of blow mold halves at said firstblow station to expand the enclosed parison; f. a second fixedly mountedblow assembly positioned to engage said second pair of blow mold halvesat said second blow station to expand the enclosed parison; g. theassemblies and means of subparagraphs b) through f) being mounted on aportable first support means which is separate from second support meanson which the means of subparagraph a) is mounted; and h. third supportmeans for supporting said first portable support means, said thirdsupport means being adjustable to position said first portable supportmeans in relation to said second support means.
 2. In the blow moldingapparatus of claim 1 wherein each of said first and second means fortransversely moving said first and second pairs of blow molds includes ablow mold transport assembly mounted on a pair of spaced apart tracksattached to said portable first support means whereby said transportassembly may be reciprocally moved.
 3. In the blow molding apparatus ofclaim 2 wherein the reciprocal movement of each of said blow moldtransport assemblies is in a straight line over a substantial portion oftheir movement.
 4. In the blow molding apparatus of claim 3 wherein saidblow mold transport assemblies move in an upwardly directed, curved pathover the terminal portion of their travel as they approach the parisonsupply station.
 5. In the blow molding apparatus of claim 3 wherein eachof said transport assemblies includes fluid powered means for openingand closing said blow mold halves.
 6. In the blow molding apparatus ofclaim 5 wherein said fluid powered means includes means for convertinglinear motion into rotary motion.
 7. In the blow molding apparatus forclaim 6 wherein said fluid is compressed air.
 8. In the blow moldingapparatus of claim 6 wherein said fluid powered means includes a cam andat least two cam followers engaging said cam.
 9. In the blow moldingapparatus of claim 8 wherein one of said cam followers is coupled to oneof said mold halves and the other of said cam followers is coupled tothe other of said mold halves.
 10. In the blow molding apparatus ofclaim 1 wherein said portable first support means is a rigid supportframe.
 11. In the blow molding apparatus of claim 10 wherein said tracksare carried by the upper portion of said rigid support frame assembly.12. In the blow molding apparatus of claim 10 wherein said support frameis removably attached to said third support means which includes meansto raise and lower said support frame.
 13. In the blow molding apparatusof claim 11 wherein a fluid powered reciprocating assembly is mounted Onsaid support frame below said transport assembly and is coupled to saidtransport assembly.
 14. In the blow molding apparatus of claim 13wherein said support frame is removably attached to said third supportmeans which includes means to raise and lower said support frame.